Network Interface Device

ABSTRACT

Roughly described: a network interface device has an interface. The interface is coupled to first network interface device circuitry, host interface circuitry and host offload circuitry. The host interface circuitry is configured to interface to a host device and has a scheduler configured to schedule providing and/or receiving of data to/from the host device. The interface is configured to allow at least one of: data to be provided to said host interface circuitry from at least one of said first network device interface circuitry and said host offload circuitry; and data to be provided from said host interface circuitry to at least one of said first network interface device circuitry and said host offload circuitry.

CROSS REFERENCE TO OTHER APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/226,453, entitled “NETWORK INTERFACE DEVICE” by Steven L. Pope, DerekRoberts, David J. Riddoch and Dmitri Kitariev, filed 19 Dec. 2018,(Atty. Docket No. LVLS 2054-2), which is a continuation-in-part of U.S.application Ser. No. 15/847,778, entitled “NETWORK INTERFACE DEVICE” bySteven L. Pope, Derek Roberts, and David J. Riddoch, filed 19 Dec. 2017,(Atty. Docket No. LVLS 2054-1), which applications are incorporatedherein by reference in their entirety.

BACKGROUND Field

This application relates to network interface devices having a fieldprogrammable gate array application.

Background

Network interface devices are known and are typically used to provide aninterface between a computing device and a network. The networkinterface device can be configured to process data which is receivedfrom the network and/or process data which is to be put on the network.

For some network interface devices, there is a drive to provideincreased specializations of designs towards specific applications.

SUMMARY

According to a first aspect, there is provided a network interfacedevice arranged to couple a host computing device to a network, saidnetwork interface device comprising: a first interface configured toreceive data from the host computing device; a first field programmablegate array application; and a transport engine for processing data,wherein the first interface is configured to: direct at least some ofthe data received from the host to the first field programmable gatearray application; and direct at least some of the data received fromthe host to the transport engine, wherein the first field programmablegate array application is configured to perform processing with respectto the at least some of the received data.

In one embodiment, the first field programmable gate array applicationis configured to pass the processed at least some of the data to thetransport engine, wherein the transport engine is configured to performprocessing of the at least some of the data received from the firstfield programmable gate array application and cause the processed datato be transmitted over the network.

In one embodiment, the network interface device comprises a secondinterface between the transport engine and the first field programmablegate array application, wherein the second interface is configured toreceive at least one of: protocol processed data packets from thetransport engine and data packets from the network, wherein the secondinterface is configured to pass the received data packets to the firstfield programmable gate array application for processing.

In one embodiment, in response to processing the received data packets,the first field programmable gate array application is configured toprovide processed data packets to at least one of: the transport enginefor protocol processing; and the second interface for transmission overthe network.

In one embodiment, the network interface device comprises a second fieldprogrammable gate array application configured to at least one of:process data received from at least one of: the first interface and thefirst programmable gate array application; and provide data processed bythe second field programmable gate array application to at least one ofthe: the first interface and the first programmable gate arrayapplication.

In one embodiment, the processing of the data received at the secondfield programmable gate array application comprises writing or readingfrom a data structure maintained by the second field programmable gatearray application.

In one embodiment, the providing data processed by the second fieldprogrammable gate array application comprises providing data read from adata structure maintained by the second field programmable gate arrayapplication to at least one of: the first interface and the firstprogrammable gate array application.

In one embodiment, in response to receiving a read request from thefirst interface or the first programmable gate array application,updating the data structure.

In one embodiment, the first interface is configured to direct datapackets of a first data flow to the field programmable gate arrayapplication and to direct data packets of a second data flow to thetransport engine.

In one embodiment, the transport engine is provided by applicationspecific integrated circuit gates within a field programmable gate arrayalso providing said first field programmable gate array application.

In one embodiment, said FPGA is configured to perform one or more of thefollowing: reduce data in one or more flows; aggregate data in one ormore flows; perform hybrid processing; detect a DDOS attack; machinelearning; perform a software defined networking function; provide anOpen Computing Language kernel offload; provide an offload function; andtake remedial action against a distributed denial of service attack.

According to a second aspect, there is provided a network interfacedevice arranged to couple a host computing device to a network, saidnetwork interface device comprising: a transport engine for performingprotocol processing of data packets received from the network, a firstfield programmable gate array application; a first interface configuredto receive processed data packets from the transport engine and to:provide at least some of the processed data packets to the fieldprogrammable gate array application for processing.

In one embodiment, the first interface is configured to: provide atleast some of the processed data packets to the host computing devicewithout being processed by the application.

In one embodiment, the first field programmable gate array applicationis configured to process the at least some of the data packets toprovide filtering.

In one embodiment, the network interface device comprises: a secondfield programmable gate array application; a second interface betweenthe transport engine and the second field programmable gate arrayapplication, wherein the second interface is configured to provide thedata packets received from the network to the second field programmablegate array application, wherein the second field programmable gate arrayapplication is configured to process the data packets and provide themto the transport engine.

In one embodiment, the processing by the second field programmable gatearray application comprises distributed denial of service (DDOS)mitigation, the first field programmable gate array applicationmaintains a data store, the processing by the first field programmablegate array application comprising updating the data store.

According to a third aspect, there is provided a network interfacedevice arranged to couple a host computing device to a networkcomprising: a first interface configured to receive data packets fromthe host computing device, the first interface comprising a first memoryand a second memory, wherein the first memory is memory mapped to ashared memory location in the host computing device, wherein the secondmemory is configured to receive data packets transferred from the host,wherein the network interface device comprises: a field programmablegate array application; and a transport engine for performing protocolprocessing of data packets, wherein the first interface is configured toprovide the data packets in the first memory to the FPGA application forprocessing by the FPGA application, wherein the first interface isconfigured to provide the data packets in the second memory to thetransport engine for protocol processing.

According to a fourth aspect, there is provided a data processing systemcomprising: a network interface device according to the third aspect;and a host computing device.

In one embodiment, the FPGA application is configured to provide data tothe host computing device, wherein the host computing device isconfigured to provide flow control over the data provided by the FPGAapplication to the host computing device.

In one embodiment, the flow control comprises credits based flowcontrol.

In one embodiment, the flow control comprises Xon/Xoff flow control.

According to a fifth aspect, there is provided a data processing systemcomprising a host computing device and a network interface devicearranged to couple the host computing device to a network, the networkinterface device comprising a field programmable gate array applicationand a transport engine, the host computing device comprising: one ormore processors; a first memory configured to receive data packets fortransmission over a network; a second memory configured to receive datapackets for delivery to the field programmable gate array application,wherein the second memory is mapped to a memory region on the networkinterface device associated with the field programmable gate arrayapplication; a transmit queue comprising a pointer to a location in thefirst memory, wherein the one or more processors are configured totransfer data from the first memory at the location pointed to by thepointer to a memory of the network interface device associated with thetransport engine.

In one embodiment, the second memory is mapped to the memory regionassociated with the field programmable gate array application using awide memory aperture.

According to a sixth aspect, there is provided a network interfacedevice arranged to couple a host computing device to a networkcomprising: a transport engine for performing protocol processing ofdata packets; a field programmable gate array application configured toprocess data packets to be sent over the network, wherein the transportengine is configured to perform protocol processing of data packets tobe sent over the network, the network interface device comprising: asecond interface configured to: receive data packets protocol processedby the transport engine; and cause the data packets to be transmittedover the network, wherein the second interface is configured toback-pressure the transport engine.

According to a seventh aspect, there is provided a network interfacedevice comprising: an interface comprising a plurality of input portsand a plurality of output ports; first network interface devicecircuitry having at least one input port and at least one portconfigured to be coupled to respective ports of the interface; hostinterface circuitry configured to interface to a host device, said hostinterface circuitry having at least one input port and at least oneoutput port configured to be coupled to respective ports of theinterface, said host interface circuitry comprising a schedulerconfigured to schedule at least one of the providing of data to the hostdevice and the receiving of data from the host; and host offloadcircuitry configured to perform an offload operation for the hostdevice, said host offload circuitry having at least one input port andat least one output port configured to be coupled to respective ports ofthe interface, wherein said interface is configured to allow at leastone of: data to be provided to said host interface circuitry from atleast one of said first network device interface circuitry and said hostoffload circuitry; and data to be provided from said host interfacecircuitry to at least one of said first network interface devicecircuitry and said host offload circuitry.

The at least one input port and said at least one output port of thehost offload circuitry may be connected via the interface only torespective ports of said host interface circuitry.

The network interface device may comprise second network interfacedevice circuitry having at least one input port and at least one outputport configured to be coupled to respective ports of the interface, saidsecond network interface device circuitry configured to perform networkinterface device operations.

The second network interface device circuitry may comprise at least onekernel.

The second network interface device circuitry may be configured toperform at least one of: an accelerator function and a flow steeringfunction.

The at least one input port and said at least one output port of thesecond network interface device circuitry may be connected via theinterface only to respective ports of said first network interfacedevice circuitry.

The host offload circuitry may comprise at least one kernel.

The host offload circuitry may be configured to support a firstcomponent of an application, said application component being configuredto at least one of provide data to and receive data from a secondcomponent of the application,

The second component of the application may be provided by said hostdevice.

The first network interface device circuitry may be configured to streamdata directly to at least one of a kernel in said network interfacedevice and a kernel in said host device.

The first network interface device circuitry may be configured to streamdata to a destination comprising at least one of said second networkinterface device circuitry and said host device.

The first network interface device circuitry may be configured toreceive data from a destination comprising at least one of said secondnetwork interface device circuitry and said host device.

The interface may comprise a cross bar switch.

The host interface circuitry may be configured to manage a plurality ofqueues of data.

According to an eighth aspect, there is provided a system comprising ahost device and a network interface device, said network interfacecomprising: an interface comprising a plurality of input ports and aplurality of output ports; first network interface device circuitryhaving at least one input port and at least one port configured to becoupled to respective ports of the interface; host interface circuitryconfigured to interface to the host device, said host interfacecircuitry having at least one input port and at least one output portconfigured to be coupled to respective ports of the interface, said hostinterface circuitry comprising a scheduler configured to schedule atleast one of the providing of data to the host device and the receivingof data from the host; and host offload circuitry configured to performan offload operation for the host device, said host offload circuitryhaving at least one input port and at least one output port configuredto be coupled to respective ports of the interface, wherein saidinterface is configured to allow at least one of: data to be provided tosaid host interface circuitry from at least one of said first networkdevice interface circuitry and said host offload circuitry; and data tobe provided from said host interface circuitry to at least one of saidfirst network interface device circuitry and said host offloadcircuitry.

The host may comprise at least one of: at least one application; and aprotocol processing function, a plurality of which are configured tooffload at least a part of respective functionality to said networkinterface device.

The host offload circuitry may be configured to provide at least one ofsaid offloaded respective functionality.

In the above, many different embodiments have been described. It shouldbe appreciated that further embodiments may be provided by thecombination of any two or more of the embodiments described above.

BRIEF DESCRIPTION OF DRAWINGS

Some embodiments will now be described by way of example only withreference to the accompanying Figures in which:

FIG. 1 shows a schematic view of a data processing system coupled to anetwork;

FIG. 2 shows a schematic view of a network interface device according toembodiments of the application;

FIG. 3 shows a schematic view of a network interface device according toembodiments of the application;

FIG. 4 shows a schematic view of a network interface device according toembodiments of the application;

FIG. 5 shows a schematic view of a network interface device according toembodiments of the application;

FIG. 6 shows a data processing system according to embodiments of theapplication;

FIG. 7 shows a schematic view of a network interface device according toembodiments of the application;

FIG. 8 shows a schematic view of part of a network interface deviceaccording to some embodiments;

FIG. 9 shows part of the arrangement of FIG. 8 with some parts shown inmore detail; and

FIG. 10 shows part of the arrangement of FIG. 8 and a part of a hostdevice.

DETAILED DESCRIPTION

The following description is presented to enable any person skilled inthe art to make and use the invention, and is provided in the context ofa particular application. Various modifications to the disclosedembodiments will be readily apparent to those skilled in the art.

The general principles defined herein may be applied to otherembodiments and applications without departing from the spirit and scopeof the present invention. Thus, the present invention is not intended tobe limited to the embodiments shown, but is to be accorded the widestscope consistent with the principles and features disclosed herein.

When data is to be transferred between two data processing systems overa data channel, such as a network, each of the data processing systemshas a suitable network interface to allow it to communicate across thechannel. Often the network is based on Ethernet technology. Dataprocessing systems that are to communicate over a network are equippedwith network interfaces that are capable of supporting the physical andlogical requirements of the network protocol. The physical hardwarecomponent of network interfaces is referred to as network interfacedevices or network interface cards (NICs).

Most computer systems include an operating system (OS) through whichuser level applications communicate with the network. A portion of theoperating system, known as the kernel, includes protocol stacks fortranslating commands and data between the applications and a devicedriver specific to the network interface devices, and the device driversfor directly controlling the network interface devices. By providingthese functions in the operating system kernel, the complexities of anddifferences among network interface devices can be hidden from the userlevel application. In addition, the network hardware and other systemresources (such as memory) can be safely shared by many applications andthe system can be secured against faulty or malicious applications.

A typical data processing system 100 for carrying out transmissionacross a network is shown in FIG. 1. The data processing system 100comprises a host computing device 101 coupled to a network interfacedevice 102 that is arranged to interface the host to network 103. Thehost computing device 101 includes an operating system 104 supportingone or more user level applications 105. The host computing device 101may also include a network protocol stack (not shown). For example, theprotocol stack may be a component of the application, a library withwhich the application is linked, or be provided by the operating system.In some embodiments, more than one protocol stack may be provided.

The network protocol stack may be a Transmission Control Protocol (TCP)stack. The application 105 can send and receive TCP/IP messages byopening a socket and reading and writing data to and from the socket,and the operating system 104 causes the messages to be transportedacross the network. For example, the application can invoke a systemcall (syscall) for transmission of data through the socket and then viathe operating system 104 to the network 103. This interface fortransmitting messages may be known as the message passing interface.

Instead of implementing the stack in the host 101, some systems offloadthe protocol stack to the network interface device 102. For example, inthe case that the stack is a TCP stack, the network interface device 102may comprise a TCP Offload Engine (TOE) for performing the TCP protocolprocessing. By performing the protocol processing in the networkinterface device 102 instead of in the host computing device 101, thedemand on the host system's 101 processor/s may be reduced. Data to betransmitted over the network may be sent by an application 105 via aTOE-enabled virtual interface driver, by-passing the kernel TCP/IP stackentirely. Data sent along this fast path therefore need only beformatted to meet the requirements of the TOE driver.

The host computing device 101 may comprise one or more processors andone or more memories. In some embodiments, the host computing device 101and the network interface device 102 may communicate via a bus, forexample a peripheral component interconnect express (PCIe bus).

During operation of the data processing system, data to be transmittedonto the network may be transferred from the host computing device 101to the network interface device 102 for transmission. In one example,data packets may be transferred from the host to the network interfacedevice directly by the host processor. The host may provide data to oneor more buffers 106 located on the network interface device 102. Thenetwork interface device 102 may then prepare the data packets andtransmit them over the network 103.

Alternatively, the data may be written to a buffer 107 in the hostsystem 101. The data may then be retrieved from the buffer 107 by thenetwork interface device and transmitted over the network 103.

In both of these cases, data is temporarily stored in one or morebuffers prior to transmission over the network.

Some embodiments relate to the transmission of data over a network froma data processing system. A data processing system could be any kind ofcomputing device, such as a server, personal computer or handhelddevice. Some embodiments may be suitable for use in networks thatoperate TCP/IP over Ethernet. In other embodiments one or more differentprotocols may be used. Embodiments may be used with any suitablenetworks, wired or wireless.

Buffer 106 may be any suitable memory, a FIFO, or set of registers. Thebuffer may be such that any operations which require modifications tothe frame (for example checksum insertion into headers) are completedbefore that portion of the frame is transferred to the MAC (media accesscontrol).

As mentioned, the protocol processing may be offloaded to the networkinterface device to be performed in the network interface. In the casethat such offloading is performed at the network interface device, itmay desirable to implement functionality on the network interface devicethat can make use of the protocol processing capabilities of the networkinterface device. By implementing such functionality in the networkinterface device instead of the host, potential improvements in latencymay be achieved by reducing the data transfer between the host and thenetwork interface device.

According to some embodiments of the application, a Field ProgrammableGate Array (FPGA) application is provided on the network interfacedevice. In some embodiments, the NIC functionality may be embedded in anFPGA. The FPGA application may be understood to be an application thatis implemented using an integrated circuit designed to be configured bya customer or designer after its manufacture. FPGAs may offer theability to deploy a circuit which provides an application specificsolution. An FPGA can allow for customization of a network interfacedevice. Such applications may be niche or small volume applications. TheFPGA is an array of programmable logic blocks. An FPGA may becharacterised as being reprogrammable at the logic element granularity.An FPGA may be regarded as being an array of gates.

A first interface (for example a Fabric interface) may be provided inthe network interface device between the FPGA application and the hostcomputing device, the first interface being configured to receive datafrom the host and pass at least some of the data to the FPGAapplication. The data received from the host over the first interfacefor delivery to the FPGA application may be any type of datatransaction. For example, the data may be a data packet having a payloadand header according to a suitable network protocol. The data packet maybe an egress data packet for transmission over the network. On the otherhand, the data may be a “read” request for access to a data structuremaintained by the FPGA application. In response to such a request (whichmay take the form of a local instructions issued to an address memorymapped to a memory accessible to the FPGA), the FPGA application mayreturn the requested data to the host via the first interface. The datareceived could, in other words, be a lookup request received from thehost. In some cases, the read operation from the host may cause sideeffects such as an update to data maintained by the FPGA application.For example, the FPGA could comprise a store/database (of, for example,a key value). The FPGA application may receive from the host an updateto the store/database from the FPGA in the form of memory “write”instructions, which may take the form of a store instruction to a mappedaddress. The write could update a data structure or cause any other sideeffect as implemented by the FPGA.

If the first interface receives data for transmission over the network,the first interface may be configured to pass some of this data to theFPGA application for processing. The first interface may pass theremaining data to a transport engine for protocol processing andtransmission over the network without it being processed by the FPGAapplication. The FPGA application may be configured to perform theprocessing of data packets it receives. In some cases (e.g. the data isfor transmission over a network), the FPGA application is configured tothen pass the processed data to the transport engine for protocolprocessing to form protocol processed data packets. Hence, theprocessing by the FPGA application is optional from the perspective ofthe first interface. The first interface has the capability to apportionwork to the FPGA application. Once the protocol processing has beenperformed, the data packets are then transmitted over the network.

A second interface may be provided in the network interface device, forinterfacing the device with the network. The second interface may be aLayer 2 Streaming Interface. The second interface is configured toreceive data packets from the FPGA application or from the transportengine and cause them to be transmitted over the network.

The network interface device is also configured to receive ingress datapackets from the network and pass them to the host or the FPGA dependingon a classification of the packets, e.g. MAC or virtual local areanetwork (VLAN).

The transport engine is configured to receive some ingress data packetsfrom the network and perform receive protocol processing of the datapacket prior to passing at least some of the data packets to the firstinterface. The first interface is configured to receive these protocolprocessed data packets from the transport engine and pass some of themto the FPGA application. The first interface may be configured to causethe remaining data packets to be transmitted to the host without beingprocessed by the FPGA application. The FPGA application may then beconfigured to perform processing of the data packets passed to it priorto the data packets being transmitted to the host via the firstinterface. The first interface may be configured to receive data packetsfrom the FPGA application that have been processed by the FPGAapplication, and to pass these processed packets to the host computingdevice. Alternatively, instead of transmitting the data packets to thehost, the FPGA application may be configured to process the data packetsby terminating them. The FPGA application may be configured to processthe data packets by consuming them. The FPGA application may process thedata packets by filtering them and passing only some of them to thehost.

In some embodiments, the second interface may be configured to receivedata packets from the network and provide them to the FPGA applicationprior to protocol processing at the transport engine. The FPGAapplication may perform the processing of the data packets and may thenpass the processed data packets to the transport engine. The transportengine is configured to receive the data packets from the FPGAapplication, protocol process them, and then pass them to the firstinterface to be transmitted to the host. The transport engine maybackpressure the second interface. A third interface, which may be a MAClayer, may also be provided between the second interface and thenetwork. The third interface may receive data packets from the networkand provide them to the second interface. The third interface may beback-pressured by the transport engine or by the second interface.

A third interface, which may be MAC layer, may also be provided betweenthe second interface and the network. The third interface may receivedata packets from the network and provide them to the second interface.

In some embodiments, the transport engine may receive egress datapackets from the host for protocol processing prior to them being passedto the FPGA application. The FPGA application may then process theprotocol processed data packets prior to passing them to the secondinterface for transmission over the network. The second interface may beconfigured to pass the data packets to the third interface, which isconfigured to cause them to be transmitted over the network. The secondinterface may be back-pressured by the third interface. The transportengine may be back pressured by the second interface or the thirdinterface.

The FPGA application may need to compete for host memory and PCIbandwidth used to communicate with the host. The FPGA application mayalso need to compete for network bandwidth. The FPGA application mayneed to compete for these resources with, for example, data flows beingsent and received between the host and the network.

The back pressuring of the transport engine or the interfaces could, forexample, be used to free up additional resources for the FPGAapplication. For example, the transport engine may be back-pressured bythe second interface. This may free up resources for the FPGAapplication communicate over the network, by reducing the proportion ofnetwork resources in use for transmitting data packets from thetransport engine.

Different techniques may be used by the network interface device forscheduling so as to allocate the resources appropriately. In oneexample, credit-base flow control may be implemented. For example, theFPGA application may have data to be written to the host. The FPGAapplication may make the transfer of data to the host in response todetermining that sufficient credits are available for the making of thetransfer of the data to the host. For example, the FPGA application mayreceive the credits from the host and, in response, to send the data tothe host. The credits may be bus credits, such as PCIe tags. The creditsmay be sent by the first interface to both the FPGA application and thetransport engine. The credits may be shared amongst the FPGA applicationand the transport engine. The credits may be shared amongst the slicesof the transport engine. By using this flow control method, the host mayexert control over the resources used by the host.

In another example XOFF/XON flow control may be implemented. Forexample, the host may transmit to the network interface device XOFF/XONcodes that indicate to the FPGA application whether or not data shouldbe transmitted from the FPGA application to the host. The FPGAapplication may transmit data to the host in response to receiving anindication to transmit. The FPGA application may continue to transmitdata to the host until an indication not to transmit is received. TheFPGA application may then resume transmission until an indication totransmit is again received.

Some embodiments may have the advantage that the network interfacedevice can be programmed to provide functions for the data packets inthe receive path or on the transmit path as a customer or designer wouldsee fit. These functions could be performed for only some or for all ofthe data packets on the receive path or transmit path.

As the FPGA application is provided with the first interface where thedata paths also interface to the host, the FPGA application may make useof data path operations. For example the data path operation may be achecksum offload operation. The first interface may allow the networkinterface device to properly schedule work between host applications andthe FPGA application. The FPGA application with this architecture isable to communicate with the other network interface device applicationsusing a relative high bandwidth and/or relative low latencyinterconnect. Some embodiments may have the advantage that the FPGAapplication is integrated within the network interface functionality.

In some embodiments, a plurality of FPGA applications may be provided inthe network interface device. The plurality of FPGA applications may beconfigured to perform different types of processing.

Some embodiments may support a significant amount of per-frame packetprocessing.

Reference is made to FIG. 2, which shows a network interface device 200according some embodiments of the application.

The network interface device functionality may be embedded in an FPGA205 in some embodiments. That FPGA 205 may have network interfacefunctionality and FPGA functionality. The FPGA functionality may providean FPGA application 240, which may programmed into the FPGA 205according to the needs of the network interface device user. The FPGAapplication 240 may, for example, provide filtering of the messages onthe receive path from the network 230 to the host. The FPGA application240 may provide a firewall.

The FPGA application 240 may be used for any suitable purpose. Forexample, the FPGA application 240 may reduce data in one or more flows.For example, the FPGA application 240 may remove duplicate messages inan arbitration application. The FPGA application 240 may alternativelyor additionally be used to aggregate data. For example the FPGA maybuffer and consolidate network captures for more efficient hostdelivery. Alternatively or additionally, the FPGA may be used for hybridprocessing. For example the FPGA may provide a toolkit to enable hybridapplications to implement fast-path processing (low-latency) on the FPGAwhile using a slice to handle slower (and more complex TCP) protocolactivity. This is also known as Delegated-Send on the transmit side. TheFPGA may be used to detect frames which are part of DDOS attack. Thoseframes may be dropped or filtered. The FPGA may alternatively oradditionally be used for machine learning with a neural network or thelike.

The FPGA may be programmable to provide the FPGA application 240 using ahigh level programming language, such as C-based languages. The highlevel programming of the FPGA may be achieved using high levelsynthesis. The FPGA application 240 may implement a neural network andperform feature extraction or classification based on incoming frames.

In some embodiments, the network interface device functionality may beimplemented as “hard” logic within the FPGA. For example, the hard logicmay be Application Specific Integrated Circuit (ASIC) gates. The FPGAapplication 240 may be implemented as “soft” logic. The soft logic maybe provided by programming the FPGA LUTs (look up tables). The hardlogic may be capable of being clocked at a higher rate as compared tothe soft logic.

The network interface device 200 includes a first interface 210configured to receive data from the host 230. The first interface 210may be a fabric interface. The first interface 210 interfaces thetransport engine 215 with the host computing device 235. The firstinterface 210 also interfaces the FPGA application 240 with the host235. The first interface may provide an application programminginterface, allowing the host 235 to perform memory read and writes tomemory associated with the FPGA application 240.

Some drivers may be associated with the memory interfaces. This allowshost applications to directly access the FPGA application 240 from thehost and make uses of the functions of the FPGA application 240 at thesame time that the FPGA is used as a network interface device. Thememory based interface may be mapped through a different PCI functionthan is used by the message passing interfaces. The message passinginterfaces typically have one function per Ethernet port. The hostsoftware may attach a driver to each function and may attach the networkstack to the interface to the network.

The network interface device 200 further comprises a transport engine215, configured to process the data packets in accordance with atransport protocol, such as TCP/IP. The transport engine 215 maycomprise a protocol stack. The transport engine 215 may comprise aplurality of slices or data pipeline, some of the slices being RX slicesconfigured to perform receive processing of the ingress data packetsreceived from the network 230, and some of the slices being TX slicesconfigured to perform transmit processing of the egress data packets tobe transmitted onto the network 230. In some embodiments, a slice may beable to handle both data to be transmitted and received data.

In the example shown, four slices are provided. However, it should beappreciated that in other embodiments, a different number of slices areused. In one embodiment, a slice may be arranged to process receiveddata or to process data to be transmitted. In other embodiments, a slicemay be arranged such that it is able to process received data and datato be transmitted. In some embodiments, the number of slices may be thesame as the number of ports. In some embodiments, there may be atransmit slice and a receive slice for each port. In some embodiments,there may not be a direct correlation between the number of ports andthe number of slices. In some embodiments, a slice can be switcheddynamically from processing received data to processing transmitted dataand vice versa.

Each slice may be regarded as a processing engine. Each slice may thusexecute micro code to implement functions such as parsing, matchingoffload and delivery semantics for the data path. The slice may act onany bit of a frame.

The slices may perform a parsing action on the data which the slice isprocessing. There may be a matching action which matches the dataagainst for example a filter and action function which performs anaction or not in dependence on the result of the matching.

The network interface device 200 also comprises a second interface 220configured to interface the transport engine 215 with the network 230and configured to interface the FPGA application 240 with the network230. The second interface maybe a layer 2 streaming interface. Thesecond interface may provide an interface to the network 230 via a thirdinterface 225. The third interface 225 may receive data packets from thesecond interface and cause them to be transmitted over the network 230.The third interface 225 may similarly receive data packets from thenetwork 230 and pass them to the second interface 220. The thirdinterface 225 may comprise a MAC interface. The third interface 225 maycomprise a plurality of MAC interfaces. The third interface 225 maycomprise one or more Physical Coding Sublayer (PCS) interfaces. Thethird interface 225 may comprise one or more Physical Medium Attachment(PMA) interfaces.

The fabric interface is configured to allow the co-resident FPGAapplication 240 to receive frames from the host. The FPGA application240 may be able to transmit frames to the work with data path processingat the same bandwidth as the host PCI.

The layer 2 streaming interface is configure to allow the FPGAapplication 240 to receive frames form any active MAC layer interfaceand to transmit frames to a data path associated with that MAC.

The network interface device may provide functionality such as flowsteering and low latency operation, hardware timestamping and clocksynchronization.

FIG. 2 shows a path that may be taken by ingress data packets upon theirreception from the network 230. The third interface 225 is configured toreceive the data packets from the network and pass them to the secondinterface 220. The second interface 220 is configured to pass the datapackets to the transport engine 215, which performs processing of thedata packets, prior to passing the processed data packets to the fabricinterface 210. The fabric interface 210 is configured to pass some ofthe data packets to the host 235, and some of the data packets to theFPGA application 240. The fabric interface may determine to pass datapackets of a first flow to the host 235 and data packets of a secondflow to the FPGA 205. The data packets received at the FPGA application240 are processed by the FPGA application 240, before being passed tothe host 235. Hence, the FPGA 205 can provide accelerator functions forsome data packets prior to them being received at the host 235.

As explained, the FPGA 205 may provide a plurality of FPGA applications.The FPGA 205 could provide a first application and a second application.In FIG. 2, it is shown that data may be directed from a first interface210 to the first field programmable gate array application 240 forprocessing. Additionally, however, the first and second interface may beconfigured to direct data to a second field programmable gate array forprocessing.

Reference is made to FIG. 7, which shows an example of a networkinterface device 700 according to embodiments of the application. Inthis case, the FPGA 705 provides a first FPGA application 715 and asecond FPGA application 710. The second interface 220 is configured toreceive the data packets from the network and provide the data packetsto the second FPGA application 710 for processing. The second FPGAapplication 710 may process the data by performing DDOS mitigation, suchas searching the data packets for a DDOS attack and taking remedialaction against a DDOS attack. The data packets may comprise updates to adata store, maintained by the first FPGA application 715. The secondFPGA application 710 is configured to provide security by searching thedata packets to detect any threats posed by the data packets and takingany action as required.

After processing by the second FPGA application 710, the second FPGAapplication 710 is configured to provide the data packets to thetransport engine 215 for protocol processing. Once the data packets havebeen processed, they are passed to a first interface, which isconfigured to provide the data packets to the first FPGA application715. The first FPGA application 715 is configured to process the datapackets. The processing by the first FPGA application 715 may compriseupdating the data store maintained by the first FPGA application 715with the data contained in the data packets.

The host may also provide queries of the data in the data storemaintained by the first FPGA application 715. In response to a query,the first FPGA application 715 may be configured to provide therequested data from the data store to the host 235.

Additionally, although not shown in FIG. 7, the first FPGA application715 may communicate with the second interface 220 to send and receivedata with the transport engine 215 and the network 230. The first FPGAapplication 715 may send data to the transport engine 215 on the receivepath or the transmit path. The first FPGA application 715 may receivedata from the transport engine 215 on the receive path or the transmitpath. Additionally, although not shown in FIG. 7, the second FPGAapplication 710 may communicate with the first interface 210 to send andreceive data with the transport engine 215 and the host 235. The secondFPGA application 710 may send data to the transport engine 215 on thereceive path or the transmit path. The second FPGA application 710 mayreceive data from the transport engine 215 on the receive path or thetransmit path.

The first FPGA application 715 and the second FPGA application 710 mayboth have access to shared state, which they may use for communicatingwith each other.

Reference is made to FIG. 3, which shows the same network interfacedevice 200 shown in FIG. 2, but, in this case, indicates a path that maybe taken by data received from the host 235. The first interface 210 isconfigured to receive data from the host 235 and to direct some of thedata to the transport engine 215 for processing without it first beingprocessed by the FPGA application 240. The first interface 210 is alsoconfigured to transfer some data to the FPGA application 240 forprocessing by the FPGA application 240. Once the data have beenprocessed by the FPGA application 240, the FPGA application 240 may beconfigured to transfer those data packets to the first interface, whichis configured to pass them to the transport engine 215 for protocolprocessing. The transport engine 215 is configured to process the datait receives to produce protocol processed data packets prior to thembeing transmitted onto the network. The protocol processed data packetsmay be passed to the second interface 220 and subsequently the thirdinterface 225 prior to their transmission onto the network 230.

As will be explained with reference to FIG. 6 below, a host applicationmay communicate directly with the FPGA application 240 via memorymapping. The host application may write to a shared memory on the host235, which is memory mapped to a memory accessible to the FPGAapplication 240. Hence, the FPGA application 240 may receive datawritten to the shared memory by the host 235. Likewise, the FPGAapplication 240 may write to the memory that is accessible to it, withthat data being automatically copied from that memory to the memory ofthe host 235 so that it received by the host application 235.

In some cases, some data may be transferred to the transport engine 215from the host 235 and some data may be transferred to the FPGAapplication 240 from the host 235 in parallel. For example, a first hostapplication may transfer data to the transport engine 215 via the firstinterface, whilst a second host application is transferring data to theFPGA application 240 at the same time.

Reference is made to FIG. 4, which shows a network interface device 400according to some embodiments of the application. The network interfacedevice 400 is similar to the network interface device 200 shown in FIGS.2 and 3, with like elements being indicated with like referencenumerals. However, FIG. 4 shows the network interface device 400 havingtwo separate MAC interfaces 405, 410. In this case, the two MACinterfaces 405, 410 may be understood to constitute the third interface.Each MAC interface may be associated with different slices of thetransport engine. For example, the first MAC interface 405 may beassociated with a first receive slice 415 a, such that data packets,which are received at the first MAC interface 405 are delivered by thesecond interface 220 to the first receive slice 415 a for receiveprocessing. The first MAC interface 405 may also be associated with afirst transmit slice 415 c, such that data packets for which transmitprocessing is carried out at the transmit slice 415 c are delivered bythe second interface 220 to the MAC interface 405 for transmission overthe network. The second MAC interface 410 may be associated with asecond receive slice 415 b, such that data packets, which are receivedat the second MAC interface 410 are delivered by the second interface220 to the second receive slice 415 c for receive processing. The secondMAC interface 410 may also be associated with a second transmit slice415 d, such that data packets for which transmit processing is carriedout at the transmit slice 415 d are delivered by the second interface220 to the second MAC interface 410 for transmission over the network.

FIG. 4 shows a path that may be taken by data packets upon receptionfrom the network 230. The data packets may be received at the thirdinterface (e.g. the second MAC interface 410) and be passed to thesecond interface 220. The second interface 200 may be configured totransfer some data packets to the transport engine 215 and other datapackets to the FPGA application 240. The FPGA application 240 isconfigured to process the data packets and pass them (e.g. via thesecond interface) to the transport engine 215. The transport engine 415is configured to process the data packets prior to passing them to thehost via the first interface 210.

The transport engine 215 may be configured to back-pressure the secondinterface. The transport engine 215 comprises one or more buffers forstoring data on which receive protocol processing is to be performed. Ifa large amount of traffic is received from the network 230, there is arisk of buffer overflow for the one or more buffers stored by thetransport engine 215. Therefore, in this case, the transport engine 215may provide an indication to the second interface 220 to reduce the rateof data transfer to the transport engine 215. The transport engine 215may be configured to monitor buffer utilization of the one or morebuffers, and if the buffer utilization gets too high to provide anindication of such to the second interface 220, which reduces the rateat which is provides data packets to the transport engine 215 forprocessing. Similarly, the second interface 220 may back-pressure thethird interface, by providing the indication that the buffer utilizationis too high to the third interface. The third interface being thenconfigured to reduce the rate at which it transfers data packets to thesecond interface 220. The back pressuring of the third interface may bespecific to the MAC interface associated with the particular slice,which is configured to perform receive processing for that MACinterface. For example, if the second receive slice 415 b determinesthat the buffer utilization of a buffer associated with this slice getstoo high, an indication of such may be provided to the second MACinterface 410, which reduces the rate of transfer to the second receiveslice 415 b.

Reference is made to FIG. 5, which shows the same network interfacedevice 400 shown in FIG. 4, but, in this case, indicates a path that maybe taken by egress data packets received from the host 235 fortransmission onto the network 230. The data packets are received fromthe host 235 and transferred via the first interface 210 to thetransport engine 215, which performs processing of the data packets andpasses the data packets to the second interface 220. The secondinterface 220 is configured to pass some of the data packets to thethird interface for transmission onto the network 230, without beingprocessed by the FPGA application 240. The second interface 220 isconfigured to pass some of the data packets to the FPGA application 240.The FPGA application 240 processes the data packets and then passes themto the third interface 410 for transmission over the network.

In this case, the second interface 220 may back-pressure the thirdinterface. The second interface 220 comprises one or more buffers forstoring data on which receive protocol processing is to be performed. Ifa large amount of traffic is received at the second interface 220 fordelivery to the network 230, there is a risk of buffer overflow for theone or more buffers stored by the second interface 220. Therefore, inthis case, the second interface 220 may provide an indication to thetransport engine to reduce the rate of data transfer to the secondinterface 220. The second interface 220 may be configured to monitorbuffer utilization of the one or more buffers, and if the bufferutilization gets too high to provide an indication of such to the secondinterface 220, which reduces the rate at which is provides data packetsto the third interface. Similarly, the third interface may back-pressurethe second interface 220, by providing an indication that the bufferutilization of the third interface is too high, the second interface 220being then configured to reduce the rate at which it transfers datapackets to the third interface.

The concepts explained with regard to FIGS. 2, 3, 4, 5, and 7 are notlimited to those specific embodiments and may be combined.

Reference is made to FIG. 6, which illustrates how data may betransferred from the host 605 to the network interface device 610. Asexplained previously, the first interface 620 is configured to receivedata from the host 605. The host 605 may make the determination as towhich of these is to apply to particular data. The host 605 may transferdata using different methods to memory associated with the firstinterface 620. For example, the host 605 may memory map data to a firstmemory 615 of the first interface 620. The first interface 620 isconfigured to provide the data in the first memory 615 to the FPGAapplication 630. Alternatively, the host 605 may transfer data to asecond memory 625 of the first interface 620. The first interface 620then being configured to provide the data in the second memory 625 tothe transport engine 635 for processing. The first memory 615 and thesecond memory 625 may each comprise one or more buffers.

The host comprise a memory 640, which is memory mapped to the memory 615on the network interface device 610. The memory mapping may be such thata user level process/host application 670, which is configured to writeto the memory 640, and the network interface device 610 both have accessto shared memory to which data is written. When a user level process 670running on the host transfers data to the memory 640, the data may beautomatically transferred from the memory 640 to the memory 615.

The communication between the FPGA application 630 and the memory 640 ofthe host is bidirectional, i.e. the FPGA application can also transferdata to the host 605 as well as receive data from the host 605. Totransfer data to the host 605, the FPGA application 630 is configured towrite data to memory 615, the data being automatically transferred tomemory 640, so that a user level process 670 running on the host mayaccess the data from the memory 640.

The host 605 comprises a memory 645 at which data may be stored fortransfer to the memory 625 of the network interface device 610. The datamay be provided to the memory 625 from a second application 675 runningon the host 605. Hence, the second application 675 may transfer datausing this socket interface to the network interface device 610. Thedata in memory 625 is provided to the transport engine. The host 605also comprises a transmit queue 650 comprising a series of pointerspointing to locations in the memory 645 from which data is to betransferred to the network interface device 610. The host may comprise aqueue 655 identifying the next available location in the memory at whichdata is to be written by the application 675. The queues 650 and 655 maycomprise FIFO buffers. The data may be stored in the buffer 645 at thenext available location—as identified by the next pointer in the queue655—by a user level process 675. A processor of the host device isconfigured to read the next pointer from the transmit queue 650 and readthe data from the buffer 645 at the location identified by the pointerand transfer the data to the network interface device 610. The networkinterface device 610 is configured to store the data in memory 625 at alocation identified by the next pointer in the receive queue 660. Thedata in memory 625 may then be provided to the transport engine 635 forprotocol processing.

The communication between the transport engine 635 and the host 605 isalso bidirectional. A similar memory transfer mechanism may beimplemented for transfer of the data from the fabric interface to thehost 605.

FIG. 6 also shows the second interface 660 and the third interface 665,for the sending and receiving of data from the network. Data may betransferred from the FPGA application 630 or the transport engine 635 tothe second interface 660, which is configured to pass the data to thethird interface 665. The third interface 665 is configured to cause thedata to be transmitted over the network. On the receive path, the datamay be received from the network at the third interface 665, and passedto the second interface 660. The second interface may transfer the datato the FPGA application 630 or to the transport engine 635.

The two data transfer methods shown in FIG. 6 may occur in parallel. Forexample, the interface used by the application 675 to transfer data tothe transport engine 635 may be active at the same time as the interfaceused by the application 670 to transfer data to the FPGA application630. Furthermore, these interfaces may be both in use by multipleapplications in parallel. A plurality of host applications may beconfigured to write to memory 645 to transfer data to the transportengine 635 and a plurality of host applications may be configured towrite to memory 640 to transfer data to the FPGA application 630. Insome examples, both of the interfaces may have associated with it adriver and a software stack.

In some cases an application may be provided in the host that may beused to transfer state between the host 605 and the FPGA application.The application may be an Open Computing Language application. A sharedmemory (e.g. a memory aperture) may be mapped onto the application. Theshared memory may be used to transfer state between parts of theapplication running on the host and parts on the FPGA. Hence, transferof state between the host and the parts on the FPGA may be achieved.

Reference is made to FIGS. 8, 9 and 10 which shows an interfacearrangement. This embodiment may be used in conjunction with orseparately from the embodiments previously described. The arrangement ofFIG. 8 is provided by an FPGA or similar device. In some embodiments, apart of the arrangement of the FIG. 8 may be implemented by an ASIC orthe like. In this scenario, the other parts may be provided by an FPGA.This is will be described in more detail with reference to FIG. 9.

Reference is first made to FIG. 8. In this arrangement, there is aninterface 800. This interface 800 may be a fabric interface such aspreviously described. In some embodiments, the interface may be aninterface which operates in accordance with the AXI (advanced eXtensibleinterface) protocol. In some embodiments, the interface may be one whichoperates in accordance with the AXI-ST (AXI-streaming) protocol.However, it should be appreciated that the Interface can operate inaccordance with any other suitable protocol in other embodiments.

The interface 800 may be regarded as providing a cross bar switchfunction.

A streaming subsystem comprising the network interface device streamingcore 802 is provided with a plurality of input ports and a correspondingplurality of output ports. These ports are referenced 816. In otherembodiments, there may be more input ports than output ports or viceversa.

In the example shown in FIG. 8, the network interface device streamingcore 802 has four input ports and four output ports. In the exampleshown in FIG. 8, two input ports and two output ports are eachassociated with a single respective buffer 814. Thus there is a one toone relationship between a port and a buffer. Two of the input ports andtwo of the output ports are each associated with buffers. Thus there isa one to two relationship between a port and two buffers. It should beappreciated that this is by way of example only.

In some embodiments, all of the ports may be associated with the samenumber of buffers. In other embodiments, such as shown in FIG. 8, theremay be a different number of buffers associated with a port.

In some embodiments, more than two buffers may be associated with agiven port.

The ports of the network interface device streaming core 802 areconfigured to communicate with respective ports 818 of the interface800.

A MDMA (multi-queue direct memory access) streaming subsystem 810 isprovided. This is configured to provide an interface to the host. Inthis example, the MDMDA streaming subsystem 810 is provided with aninput port and an output port 828. In other embodiments the MDMAstreaming subsystem may be provided with more two ports. These ports ofthe MDMA streaming subsystem connect to respective ports 830 of theinterface 800. In this example, each port is associated with threebuffers 826. This is by way of example only and in other embodiments, aport of the stream may be associated with more or less than threebuffers.

The streaming subsystem 810 includes its own local scheduler to manageDMA queues. This however will be described in more detail later.

One or more streaming subsystems with computer kernels 806 and 808 arealso provided. In the example shown in FIG. 8, there are two suchstreaming subsystems with compute kernels 806 and 88. It should beappreciated that there may be more or less than two such streamingsubsystems. In some embodiments, the number of such streaming subsystemsmay change during operation. This may be dependent on requirements ofthe host system. A streaming subsystem with computer kernels may beadded to and/or removed from a data path.

In this example, each of the streaming subsystems with compute kernels806 and 808 is provided with an input port and output port which arereferenced 834. These respective ports are configured to communicatewith respective ports 836 provided on the interface. Each of these portsis shown with a single buffer 832. However, this is by way of exampleonly and in other embodiments more than one buffer may be associatedwith a given port.

In some embodiments, there may be a single streaming subsystem withcompute kernels which is capable of supporting a plurality of functions.In such an embodiment, the streaming subsystem with compute kernels maybe provided with more than two ports.

It should be appreciated that the streaming subsystem with computekernels 806 and 808 are configured only to communicate with the MDMAstreaming subsystem 810 in some embodiments. By configuring thecommunication path in the way, the host is able to configure functionswhich are to be performed on the network interface device without havingto compete for access to resource which is used for communicationsbetween the network interface streaming core and the stream subsystemwith network interface device extensions kernels.

A streaming subsystem with network interface device extension kernels804 is provided in some embodiments. In this example, the streamingsubsystem with network interface device extension kernels 804 isprovided with two input ports and two output ports. The ports arereferenced 822. These ports 822 are connected to respective ports 824 ofthe interface 800. In other embodiments, there may be more than two orless than two input ports and/or output ports.

In this example, each port is associated with three buffers 820.However, this is by way of example only and in some embodiments, eachport may be associated with less than three buffers or more than threebuffers.

The number of ports of the network interface device streaming core 802which are active may be dependent on the number of functions beingperformed by this core and may dynamically change. In other embodiments,there may be more than one network interface device streaming core whichmay be added to and/or removed from a data path. Where there is thepossibility of more than one network interface device streaming core,each network interface device streaming core may be associated with afewer number of ports. For example, a pair of ports may be provided witheach network interface device streaming core. In other embodiments,where there is the possibility of more than one network interface devicestreaming core, different instances may be provided with differingnumbers of ports.

In some embodiments, data from one or more of the ports of the streamingsubsystem containing the network interface device core may be receivedvia the interface 800 at the one or more ports of the streamingsubsystem with network interface device extension cores. In someembodiments, data is received at one or more of the ports of thestreaming subsystem containing the network interface device core via theinterface 800 from one or more port of the streaming subsystem withnetwork interface device extension cores.

It should be appreciated that the streaming subsystem with networkinterface device extension kernels is, in some embodiments, configuredto only communicate with the with respective ports of the streamingsubsystem containing the network interface device streaming core.

In some embodiments, the number of such streaming subsystems withnetwork interface device extension kernel functions may change duringoperation. This may be dependent on requirements of the host system. Astreaming subsystem with network interface device extension kernelfunctions may be added to and/or removed from a data path.

In some embodiments, data from one or more of the ports of the streamingsubsystem containing the network interface device core may be receivedvia the interface 800 at the one or more ports of the MDMA streamingsubsystem 810. In some embodiments, data is received at one or more ofthe ports of the streaming subsystem containing the network interfacedevice core via the interface 800 from one or more port of the MDMAstreaming subsystem.

One or more the buffers previously discussed may be provided by a FIFO(first in first out) buffer. Separate buffers may be provided for thereceive data and for the transmit data. For each data flow there may beone or more pairs of transmit and receive buffers.

The size of the buffers may be sized in dependence on the size of themaximum transmit unit MTU.

One or more of the links between two ports may be provided a linkoperating in accordance with the AXI-ST protocol or any other suitableprotocol. In some embodiments, all of the links to the external ports ofthe interface 800 operate using the same protocol.

The links to the external ports of the interface may support data ratesof 200 Gb in some embodiments. In other embodiments, data rates of moreof less than this value may be supported.

In the embodiment shown in FIG. 8, the interface 800 may be a 9 inputport by 9 output port device. In other embodiments, the interface mayhave any other suitable size. In some embodiments, the fabric orinterface may be made up from two or more independent sub-fabrics. Inthe case of a 9×9 port fabric, this may be made up of a 3×3 and 5×5fabric

In some embodiments the interface 800 may have a port to the MDMAstreaming subsystem which has a simple single cycle round robin arbiter.

One or more of the streaming subsystem with network interface devicewith extension kernel and the streaming subsystem may be implemented bya transmit and/or receive slice such as previously described.

One or more of the streaming subsystem with network interface devicewith extension kernel and the streaming subsystem may be implemented byan FPGA application such as previously described.

Reference is made to FIG. 9 which shows the arrangement of FIG. 8 butwith the components of the MDMA streaming subsystem shown in moredetail. The MDMA streaming subsystem comprises MDMA function 906 whichis configured to receive data from and transmit data to the interface800. The QDMA function may provide functions such as receive sideprocessing and/or the like and/or may provide a queue function. Datawhich is to be output to the interface 100 may be received from the MDMAfunction 906 which may be provided with data received from a host via aPCIe or the like interface 904. Data which is received from theinterface 800 is provided to the MDMA function which may provide thedata to the host via the PCI or the like interface.

A MDMA source scheduler 902 is provided to schedule or arbitrate thedata which is to be output to the interface. A MDMA destinationscheduler 908 is provided to schedule or arbitrate the data which is tobe received from the interface. The MDMA function may comprise a PCI orthe like core.

In some embodiments, the functions of the network interface devicestreaming core and/or the MDMA streaming function may be provided by anASIC (application specific integrated circuit) or similar arrangement.AXI ST fabric features may be used in some embodiments to supportarbitration/scheduling. In some embodiments, a channel select field maybe provided via dedicated lines. This may be used on the link between acycle-arbiter and destination.

Some embodiments may use a credit packet passing from a destination to asource to control scheduling. Some embodiments may use a credit packetpassing from the source to the destination. The credit packets may runon the same busses as data packets in some embodiments.

Some embodiments may use a packet header which may comprise one or moreof: a packet type: routing information; a scheduler flow identifierwhich is used by the scheduler; and length information.

The packet type may indicate if the packet is a data packet, a creditpacket, a configuration capsule, a barrier packet and/or any othersuitable packet type.

In some embodiments the routing information may indicate how a packetshould get from the source to the destination through the fabric orinterface.

The network interface device streaming core may provide the basicnetwork interface device in accordance with for example IP protocols.The streaming subsystem with network interface device with extensionkernel allows the network interface device to provide functionsdepending on the context in which the network interface device is beingused. For example the streaming subsystem with network interface devicewith extension kernel can provide support for specific programminglanguages not supported by the core. By way of example only, this may beP4 language and/or the like. The streaming subsystem with networkinterface device with extension kernel may allow for flow steeringand/or acceleration functions to be performed.

The streaming subsystem with compute kernels may provide functions forthe host. By way of example, this function may be an accelerationfunction or the providing of a key data base.

Reference is made to FIG. 10. FIG. 10 shows how the MDMA function 810provides an interface to the host 930. The PCIe interface 904 of theMDMA function 810 is configured to interface with a PCIe interface 922of the host.

As shown schematically in FIG. 10, there is an application 934 with acompute offload requirement. This application 934 thus offloads to thenetwork interface device a function. This offloaded function may beprovided by one or more streaming subsystems with computer kernels 806and 808 such as previously described in relation to FIGS. 8 and 9.

As shown schematically in FIG. 10, there is a protocol processing stack932 with at least a partial offload to the network interface device.This offloaded function may be provided by one or more streamingsubsystems with computer kernels 806 and 808 such as previouslydescribed in relation to FIGS. 8 and 9. In other embodiments, theoffloaded protocol function may at least partially be implemented by thestreaming subsystem with network interface device extension kernels 804such as previously described in relation to FIGS. 8 and 9.

There may of course be more than one application on the host devicewhich is configured to offload at least a part of its functionality tothe network interface device.

In some embodiments, the protocol processing stack may be such thatthere is no offload of functionality to the network interface device.

In some embodiments, each of the applications in the host and/or theprotocol processing stack may be provided with a respective driver stack(not shown), each of which is attached to a different PCI functionwithin the interface.

It should be appreciated that the arrangements shown in FIGS. 8, 9 and10 may be used at least partially in conjunction with at least a part ofany of the previous embodiments.

It should be appreciated that one or more of the slices discussedpreviously may be used in conjunction with the arrangement of FIGS. 8, 9and 10.

One or more slices may be implemented by the FPGA and/or one or moreslices may be implemented in ASIC.

The applicant hereby discloses in isolation each individual featuredescribed herein and any combination of two or more such features, tothe extent that such features or combinations are capable of beingcarried out based on the present specification as a whole in the lightof the common general knowledge of a person skilled in the art,irrespective of whether such features or combinations of features solveany problems disclosed herein, and without limitation to the scope ofthe claims. The applicant indicates that aspects of the presentinvention may consist of any such individual feature or combination offeatures. In view of the foregoing description it will be evident to aperson skilled in the art that various modifications may be made withinthe scope of the invention.

1. A network interface device comprising: an interface coupled to i)first network interface device circuitry, ii) host interface circuitry,and iii) host offload circuitry, the interface comprising a plurality ofports; the first network interface device circuitry having at least oneport configured to be coupled to respective port of the interface; thehost interface circuitry configured to interface to a host device, saidhost interface circuitry having at least one port configured to becoupled to respective port of the interface, said host interfacecircuitry comprising a scheduler configured to schedule at least one ofthe providing of data to the host device and the receiving of data fromthe host; and the host offload circuitry configured to perform anoffload operation for the host device, said host offload circuitryhaving at least one port configured to be coupled to respective port ofthe interface.
 2. A network interface device as claimed in claim 1,wherein at least one input port and at least one output port of the hostoffload circuitry are connected via the interface only to respectiveports of said host interface circuitry.
 3. A network interface device asclaimed in claim 1, comprising second network interface device circuitryhaving at least one input port and at least one output port configuredto be coupled to respective ports of the interface, said second networkinterface device circuitry configured to perform network interfacedevice operations.
 4. A network interface device as claimed in claim 3,wherein said second network interface device circuitry comprises atleast one kernel.
 5. A network interface device as claimed in claim 3,wherein said second network interface device circuitry is configured toperform at least one of: an accelerator function and a flow steeringfunction.
 6. A network interface device as claimed in claim 3, whereinsaid at least one input port and said at least one output port of thesecond network interface device circuitry are connected via theinterface only to respective ports of said first network interfacedevice circuitry.
 7. A network interface device as claimed in claim 1,wherein said host offload circuitry comprises at least one kernel.
 8. Anetwork interface device as claimed in claim 1, wherein the host offloadcircuitry is configured to support a first component of an application,said application component being configured to at least one of providedata to and receive data from a second component of the application, 9.A network interface device as claimed in claim 8, wherein said secondcomponent of said application is provided by said host device.
 10. Anetwork interface device as claimed in claim 1, wherein first networkinterface device circuitry is configured to stream data directly to atleast one of a kernel in said network interface device and a kernel insaid host device.
 11. A network interface device as claimed in claim 3,wherein first network interface device circuitry is configured to streamdata to a destination comprising at least one of said second networkinterface device circuitry and said host device.
 12. A network interfacedevice as claimed in claim 3, wherein first network interface devicecircuitry is configured to receive data from a destination comprising atleast one of said second network interface device circuitry and saidhost device.
 13. A network interface device as claimed in claim 1,wherein said interface comprises a cross bar switch.
 14. A networkinterface device as claimed in claim 1, wherein said host interfacecircuitry is configured to manage a plurality of queues of data.
 15. Asystem comprising a host device and a network interface device, saidnetwork interface comprising: an interface coupled to i) first networkinterface device circuitry, ii) host interface circuitry, and iii) hostoffload circuitry, the interface comprising a plurality of ports; thefirst network interface device circuitry having at least one portconfigured to be coupled to respective port of the interface; the hostinterface circuitry configured to interface to the host device, saidhost interface circuitry having at least one port configured to becoupled to respective port of the interface, said host interfacecircuitry comprising a scheduler configured to schedule at least one ofthe providing of data to the host device and the receiving of data fromthe host; and the host offload circuitry configured to perform anoffload operation for the host device, said host offload circuitryhaving at least one port configured to be coupled to respective port ofthe interface.
 16. A system as claimed in claim 15, wherein said hostcomprises at least one of: at least one application; and a protocolprocessing function, a plurality of which are configured to offload atleast a part of respective functionality to said network interfacedevice.
 17. A system as claimed in claim 16, wherein said host offloadcircuitry is configured to provide at least one of said offloadedrespective functionality.